Application of Molecular Hydrogen in Heart Surgery under Cardiopulmonary Bypass.
人工心肺下心臓手術における分子状水素吸入が酸化ストレスマーカーに与える影響
Abstract
This prospective study examined the influence of inhaled molecular hydrogen on lipid peroxidation during cardiac valve surgery performed under cardiopulmonary bypass (CPB). Twenty patients were divided into a hydrogen inhalation group (n=11; 1.5–2.0% H2 delivered via ventilator circuit from intubation through surgery) and a control group (n=9; no H2). Blood samples were collected at four time points: after anesthesia induction, before CPB, after CPB termination, and 24 hours postoperatively. Lipid peroxidation was assessed via diene conjugates (DC), triene conjugates (TC), and Schiff bases (SB). In the hydrogen group, arterial TC and SB levels declined relative to baseline before CPB initiation and at 24 hours postoperatively, while venous DC elevation before CPB normalized by the post-CPB stage. The control group showed progressive increases in arterial SB and elevated venous TC and SB at 24 hours. The most pronounced reduction in oxidative stress markers in the hydrogen group occurred on postoperative day one, supporting the potential of intraoperative H2 inhalation as a safe antioxidant adjunct in cardiac surgery.
Mechanism
Inhaled molecular hydrogen is proposed to scavenge reactive oxygen species generated during cardiopulmonary bypass, thereby reducing lipid peroxidation end-products such as triene conjugates and Schiff bases in both arterial and venous blood.
Bibliographic
- Authors
- Danilova DA, Brichkin YD, Medvedev AP, Pichugin VV, Fedorov SA, Taranov EV, et al.
- Journal
- Sovrem Tekhnologii Med
- Year
- 2021
- PMID
- 34513069
- DOI
- 10.17691/stm2021.13.1.09
- PMC
- PMC8353690
Tags
Delivery context
In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.
Safety notes
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